JP2022174312A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a photoluminescence less likely to occur in an organic layer located in a region other than a light emitting portion.

SOLUTION: A light emitting unit 140 is formed on a part of a first surface of a substrate 100, and includes a first electrode 110, a second electrode 130, and an organic layer 120. The second electrode 130 covers the first electrode 110. The organic layer 120 is located between the first electrode 110 and the second electrode 130. The organic layer 120 is continuously formed from a region overlapping with the first electrode 110 to a portion located around the first electrode 110. The organic layer 120 includes a phosphorescent material. Specifically, a light emitting layer of the organic layer 120 is formed of not a fluorescent material but a phosphorescent material .

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to light emitting devices.

In recent years, development of light-emitting devices using organic EL has progressed. This light-emitting device is used as a lighting device or a display device, and has a structure in which an organic layer is sandwiched between a first electrode and a second electrode. In general, a transparent material is used for the first electrode, and a metal material is used for the second electrode.

As one of light-emitting devices using organic EL, there is a technique described in Patent Document 1. In the technique disclosed in Patent Document 1, the second electrode is provided only in a part of the pixel in order to give the display device using the organic EL light transparency (see-through). In such a structure, the regions located between the plurality of second electrodes transmit light, so that the display device can have light transmissive properties. Note that in the technique described in Patent Document 1, a translucent insulating layer is formed between the plurality of second electrodes in order to define pixels. In Patent Document 1, inorganic materials such as silicon oxide and resin materials such as acrylic resin are exemplified as materials for the insulating layer.

JP 2011-23336 A

When an organic layer that becomes a light-emitting layer is also formed in a region other than the light-emitting portion, when external light is incident on the organic layer located in this region, the external light may be absorbed by the organic layer to cause photoluminescence. be. In this case, the light transmittance of the display device is lowered.

One example of the problem to be solved by the present invention is to make it difficult for photoluminescence to occur in the organic layer located in the region other than the light emitting portion when the organic layer is formed in the region other than the light emitting portion.

A first invention comprises a translucent substrate,
a light-emitting portion having a first electrode, a second electrode, and an organic layer positioned between the first electrode and the second electrode, and formed on the first surface of the substrate;
with
The light-emitting device, wherein the organic layer is continuously formed over a region on the first electrode and a portion located around the first electrode, and the peak of the light absorption region of the organic layer does not fall within a range of 480 nm to 580 nm. is.

A second aspect of the present invention is a substrate that is translucent and has a light transmittance of 20% or less for light having a first wavelength or less;
a light-emitting portion having a first electrode, a second electrode, and an organic layer positioned between the first electrode and the second electrode, and formed on the first surface of the substrate;
with
The organic layer is formed continuously over a region on the first electrode and a portion located around the first electrode, and the peak wavelength of the light absorption region of the organic layer is equal to or less than the first wavelength. A light emitting device.

A third invention is a translucent substrate,
a light-emitting portion having a first electrode, a second electrode, and an organic layer positioned between the first electrode and the second electrode, and formed on the first surface of the substrate;
with
The organic layer is formed only in a region between the first electrode and the second electrode, and the light-emitting body constituting the light-emitting layer of the organic layer is a light-emitting device containing at least a phosphorescent material.

A fourth invention is a translucent substrate,
a light-emitting portion having a first electrode, a second electrode, and an organic layer positioned between the first electrode and the second electrode, and formed on the first surface of the substrate;
with
The organic layer is formed only in a region between the first electrode and the second electrode, and the light-emitting device constituting the light-emitting layer of the organic layer is a phosphorescent material.

1 is a cross-sectional view showing the configuration of a light emitting device according to an embodiment; FIG. 1 is a cross-sectional view showing the configuration of a light-emitting device according to Example 1; FIG. FIG. 10 is a cross-sectional view of a light emitting device according to Example 2; FIG. 4 is a plan view of the light emitting device shown in FIG. 3;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in all the drawings, the same constituent elements are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

FIG. 1 is a cross-sectional view showing the configuration of a light emitting device 10 according to an embodiment. A light-emitting device 10 according to an embodiment is, for example, a lighting device or a display device, and includes a substrate 100 and a light-emitting section 140 . The light emitting part 140 is formed on the first surface of the substrate 100 and includes a first electrode 110 , a second electrode 130 and an organic layer 120 . A second electrode 130 covers the first electrode 110 . The organic layer 120 is located between the first electrode 110 and the second electrode 130 . The organic layer 120 is formed continuously from a region overlapping the first electrode 110 to a portion located around the first electrode 110 . The peak of the light absorption region of the organic layer 120 does not lie between 480 nm and 600 nm. Specifically, organic layer 120 includes a phosphorescent material. More specifically, a part or all of the light-emitting body constituting the light-emitting layer of the organic layer 120 is formed of a phosphorescent material that mainly emits phosphorescence by being excited by the recombination energy of holes and electrons. . A detailed description will be given below.

The substrate 100 is, for example, a substrate that transmits visible light, such as a glass substrate or a resin substrate. When the substrate 100 is a glass substrate, the substrate 100 contains sodium oxide, calcium oxide, and silicon oxide in a total amount of 80% by weight or more. By doing so, the light transmittance of the substrate 100 at the first wavelength or less (eg, 400 nm or less) can be reduced (eg, 20% or less). The substrate 100 may have flexibility. When flexible, the thickness of the substrate 100 is, for example, 10 μm or more and 1000 μm or less. The substrate 100 is, for example, polygonal such as rectangular or circular. When the substrate 100 is a resin substrate, the substrate 100 is formed using, for example, PEN (polyethylene naphthalate), PES (polyether sulfone), PET (polyethylene terephthalate), or polyimide. Further, when the substrate 100 is a resin substrate, an inorganic barrier film such as SiN _x or SiON is formed on at least one surface (preferably both surfaces) of the substrate 100 in order to prevent moisture from permeating the substrate 100. It is preferable to be

A light emitting part 140 is formed on one surface of the substrate 100 . The light emitting section 140 has a configuration in which a first electrode 110, an organic layer 120, and a second electrode 130 are laminated in this order. When the light-emitting device 10 is a lighting device, the plurality of light-emitting portions 140 extend linearly. On the other hand, when the light-emitting device 10 is a display device, the plurality of light-emitting units 140 are arranged to form a matrix, or form segments or display a predetermined shape (for example, to display an icon). It may be. A plurality of light emitting units 140 are formed for each pixel.

The first electrode 110 is a transparent electrode having optical transparency. The material of the transparent electrode is a metal-containing material such as metal oxide such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), IWZO (Indium Tungsten Zinc Oxide), and ZnO (Zinc Oxide). The thickness of the first electrode 110 is, for example, 10 nm or more and 500 nm or less. The first electrode 110 is formed using, for example, sputtering or vapor deposition. The first electrode 110 may be a carbon nanotube or a conductive organic material such as PEDOT/PSS.

The organic layer 120 has a light-emitting layer. The organic layer 120 has, for example, a structure in which a hole injection layer, a light emitting layer, and an electron injection layer are laminated in this order. A hole transport layer may be formed between the hole injection layer and the light emitting layer. An electron transport layer may be formed between the light emitting layer and the electron injection layer. The organic layer 120 may be formed by a vapor deposition method. At least one layer of the organic layer 120, for example, the layer in contact with the first electrode 110, may be formed by a coating method such as an inkjet method, a printing method, or a spray method. In this case, the remaining layers of the organic layer 120 are formed by vapor deposition. Also, all layers of the organic layer 120 may be formed using a coating method.

A part or all of the light-emitting body constituting the light-emitting layer of the organic layer 120 is formed using a phosphorescent material. By doing so, the peak of the light absorption region of the organic layer 120 becomes smaller than 480 nm to 580 nm. This peak is located, for example, below 400 nm. In addition, the peak wavelength of the emission spectrum in photoluminescence in the organic layer 120 is out of the wavelength range of 480 nm to 580 nm. Here, the substrate 100 is configured such that the first wavelength described in the description of the substrate 100 is greater than the peak wavelength of the light absorption region of the organic layer 120 . In this way, photoluminescence is less likely to occur in the organic layer 120 due to external light.

The organic layer 120 is formed continuously on the first electrode 110 and on a region of the substrate 100 at least around the first electrode 110 .

The second electrode 130 is made of, for example, a metal selected from the first group consisting of Al, Au, Ag, Pt, Mg, Sn, Zn, and In, or an alloy of metals selected from the first group. contains a metal layer. In this case, the second electrode 130 has light shielding properties. The thickness of the second electrode 130 is, for example, 10 nm or more and 500 nm or less. However, the second electrode 130 may be formed using the material exemplified as the material of the first electrode 110 . The second electrode 130 is formed using, for example, sputtering or vapor deposition. In the example shown in this figure, the light emitting device 10 is wider than the first electrode 110 . Therefore, when viewed from the direction perpendicular to the substrate 100, the entire first electrode 110 is overlapped and covered with the second electrode 130 in the width direction.

An edge of the first electrode 110 is covered with an insulating film 150 . The insulating film 150 is made of, for example, a photosensitive resin material such as polyimide, and surrounds a portion of the first electrode 110 that serves as the light emitting portion 140 . A widthwise edge of the second electrode 130 is located on the insulating film 150 . In other words, when viewed from the direction perpendicular to the substrate 100 , part of the insulating film 150 protrudes from the second electrode 130 . In the example shown in this figure, the organic layer 120 is also formed on and on the side surfaces of the insulating film 150 .

A plurality of light emitting units 140 are formed on the first surface of the substrate 100 so as to be spaced apart from each other. The light emitting device 10 has a first region 102 and a second region 104 . The first region 102 is a region that includes the organic layer 120 and does not include the insulating film 150 among the regions between the plurality of light emitting units 140 . The second region 104 is a region including the organic layer 120 and the insulating film 150 among the regions between the plurality of light emitting units 140 . The area of the first region 102 is larger than the area of 104 . In cross-sectional view, the width of the first region 102 is greater than the width of the second region 104 .

In the example shown in this figure, the light emitting device 10 further has a third region 106 . The third region 106 is a region that includes the organic layer 120 and the insulating film 150 and overlaps the second electrode 130 among the regions between the plurality of light emitting units 140 .

Next, a method for manufacturing the light emitting device 10 will be described. First, the first electrode 110 is formed on the substrate 100 using, for example, a sputtering method. Next, the first electrode 110 is formed into a predetermined pattern using photolithography. An insulating layer 150 is then formed on the edge of the first electrode 110 . For example, when the insulating film 150 is made of a photosensitive resin, the insulating film 150 is formed into a predetermined pattern through exposure and development processes. Next, the organic layer 120 and the second electrode 130 are formed in this order. When the organic layer 120 includes a layer formed by vapor deposition, this layer is formed in a predetermined pattern, for example using a mask. The second electrode 130 is also formed in a predetermined pattern by using a mask, for example. After that, the light emitting section 140 is sealed using a sealing member (not shown).

In this embodiment, the light transmittance of the first area 102 is higher than the light transmittance of the second area 104 . The area of the first region 102 is larger than the area of the second region 104 . For this reason, the light-emitting device 10 has a certain or more light transmittance.

In this embodiment, the light-emitting layer that constitutes the organic layer 120 contains a phosphorescent material and does not contain a fluorescent material. In this way, the peak wavelength of the light absorption region in the organic layer 120 is out of the wavelength range of 480 nm to 580 nm. On the other hand, the light-emitting device 10 is a device that emits visible light, and the material of the substrate 100 and the like is designed to have high translucency in the wavelength range of 480 nm to 580 nm. Therefore, photoluminescence is less likely to occur in the organic layer 120 . Therefore, it is possible to prevent the light transmittance of the light emitting device 10 from deteriorating. Furthermore, the peak wavelength of the emission spectrum of photoluminescence in the organic layer 120 is positioned outside the range of 480 nm to 580 nm. Therefore, even if photoluminescence occurs in the organic layer 120, it is difficult for people to visually recognize the light generated by the photoluminescence. Therefore, it is possible to further suppress the deterioration of the light transmittance of the light emitting device 10 .

(Example 1)
FIG. 2 is a cross-sectional view showing the configuration of the light emitting device 10 according to Example 1. As shown in FIG. The light-emitting device 10 according to this example has the same configuration as the light-emitting device 10 according to the embodiment, except that the conductive portion 170 is provided.

The conductive part 170 is, for example, an auxiliary electrode of the first electrode 110 and is in contact with the first electrode 110 . The conductive part 170 is made of a material having a lower resistance value than the first electrode 110, and is made of, for example, at least one metal layer. The conductive part 170 has a structure in which a first metal layer such as Mo or Mo alloy, a second metal layer such as Al or Al alloy, and a third metal layer such as Mo or Mo alloy are laminated in this order. there is The second metal layer is the thickest of these three metal layers.

The conductive portion 170 is covered with the insulating film 150 . Therefore, it is possible to prevent the conductive portion 170 from being short-circuited to the insulating film 150 .

The timing of forming the conductive portion 170 is after forming the first electrode 110 and before forming the insulating film 150 . The conductive portion 170 is formed, for example, as follows. First, a conductive layer to be the conductive portion 170 is formed in this order using a film formation method such as sputtering. Next, a resist pattern (not shown) is formed on this conductive layer, and the conductive layer is etched (for example, wet etching) using this resist pattern as a mask. Thereby, the conductive portion 170 is formed.

Also according to the present example, it is possible to suppress the deterioration of the light transmittance of the light emitting device 10 as in the embodiment. Moreover, since the conductive portion 170 is formed on the first electrode 110, the resistance value of the first electrode 110 can be reduced.

(Example 2)
FIG. 3 is a cross-sectional view of the light emitting device 10 according to Example 2. FIG. 4 is a plan view of the light emitting device 10 shown in FIG. 3. FIG. FIG. 3 corresponds to the AA section of FIG. The light-emitting device 10 according to this example has the same configuration as the light-emitting device 10 according to either the embodiment or the first example, except that it includes a plurality of light-emitting units 140 .

Specifically, the light-emitting device 10 is a lighting device and has a plurality of linear light-emitting portions 140 . The plurality of light emitting units 140 are arranged on the first surface of the substrate 100 apart from each other. Specifically, the plurality of light emitting portions 140 are linear and extend in the same direction. The organic layer 120 is also formed in a region of the first surface of the substrate 100 located between the plurality of light emitting units 140 . In other words, the organic layer 120 is continuously formed on the plurality of light emitting units 140 and the regions therebetween.

Also according to this example, it is possible to suppress short-circuiting between the first electrode 110 and the second electrode 130, as in the embodiment. In addition, since the organic layer 120 is continuously formed on the plurality of light emitting portions 140 and the regions therebetween, it is not necessary to use a mask having a fine pattern when forming the organic layer 120 . Therefore, the cost of manufacturing the light emitting device 10 can be reduced.

Although the embodiments and examples have been described above with reference to the drawings, these are examples of the present invention, and various configurations other than those described above can be adopted.

10 Light Emitting Device 100 Substrate 102 First Region 104 Second Region 110 First Electrode 120 Organic Layer 130 Second Electrode 140 Light Emitting Part 150 Insulating Film 170 Conducting Part

Claims (4)

a translucent substrate;
a plurality of light emitting units spaced apart from each other on the first surface of the substrate;
a plurality of light-transmitting portions positioned between the plurality of light-emitting portions;
with
each of the plurality of light emitting units includes a first electrode, a second electrode, and an organic layer positioned between the first electrode and the second electrode;
The light-emitting device, wherein the organic layer includes a phosphorescent material and is continuously positioned over the plurality of light-emitting portions and the plurality of light-transmitting portions. The light emitting device according to claim 1,
The light-emitting device, wherein the plurality of light-emitting portions each have a linear shape and extend in the same direction. The light emitting device according to claim 1 or 2,
The light-emitting device, wherein the peak wavelength of the light absorption region of the organic layer is 400 nm or less. In the light emitting device according to any one of claims 1 to 3,
An insulating film surrounding the light emitting unit is provided,
The first surface of the substrate has a first region that does not include the light emitting portion and the insulating film but includes the organic layer, and a second region that does not include the light emitting portion and includes the insulating film and the organic layer. ,
The light emitting device, wherein the area of the first region is larger than the area of the second region.

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